Magnetic properties of ferromagnetic Heusler alloy Co2NbGa

Abstract

The compound Co2NbGa crystallizes in the Heusler-type structure. Magnetization measurements of Co2NbGa have been made under ambient pressure using a SQUID magnetometer. The spontaneous magnetic moment at 5 K and the Curie temperature are 1.81 μB/f.u. and 351 K, respectively. Many magnetic properties of the itinerant electron ferromagnets are explained by the Takahashi’s spin fluctuation theory. In the Takahashi’s spin fluctuation theory, spectral parameters of spin fluctuations, T0 and TA, are involved in various magnetic properties derived theoretically. In this work, we estimated T0 and TA of Co2NbGa by using the results of magnetization measurements at 5 K: T0 = 2.1 × 103 K and TA = 4.7 × 103 K. This experiment proved that the squared spontaneous magnetization Ms(T)2 is proportional to T2 at low temperature. The TA value estimated from the Ms(T)2 vs. T2 curve is 6.6 × 103 K. Furthermore, the field-induced magnetization M4 around TC is found to be proportional to H/M in the low magnetic field region.